Let-off for looms



Dec. 31, 1929. E. R. HOLMES 1,741,300

LET-OFF FOR LOOMS FiledJan. 6. 1928 zsheets sheet 1 MW-i M filter/19's lire/liar E. R. HOLMES LET Filed Jan. 1928 Dec. 31, 1929.

Patented Dec. 31, 1929 UNITED' ST"A"-'lsEs=- ELBRIDGE It. HOLMES, OF VTORCESTEB; MASSACl-IUSETTS,- ASSIGNOR: TO CROMPTON 85 KNOWLES LOOM WORKS, OF WORCESTER, MASSACHUSETTS,

MASSACHUSETTS rnrsur curios A CORPORATION OF LET-OFF FOR. LOOMS 1 Application filed January 6, 1928. Serial 'No. 244,949.

This invention relates to improvements in let-offs for-looms and it is the general object of the invention to provide a uniformly tensioned let-01f which will operate through friction disks to give a smooth action to the warp beam and to permit the latter to be mounted in a fixed position on the loom frame.

In my co-pending application Ser. No. 238,151 I have shown a let-off motion for looms wherein the warp threads are led directly from'the beam to the harnesses without being led over the ordinary whip roll. Such a construction is desired by certain manufacturers-of silk inasmuch as there is less likelihood of crossovers and resultant increases in the tension of warp threads which is likely to happen when a .whip roll is used. The aforesaid let-off employs a set of friction disks which are moved relatively to each other by means of a screw regulated in its action by the warp tension, the screw and disks movingas a whole about the axis of the warp beam as a center. As. the warp beam gets smaller-in diameter it is necessary that it be raised so that the plane of the warp threads shall be held at a comparatively fixed level. There are instances wherein this raising of thewarp beam is objectionable and wherein the use of a whip roll need not necessarily interfere seriously with the character of the clothibein'g woven and it is an important object of my present invention to provide a let-oif fo'r a warp beam which moves about a fixed axis combined with friction disks which-also move aboutfixed axes, said disks to. be operated by a screw the action of which is regulated by a whip roll.

It is a further object of my present inven tionto provide a let-off wherein an auxiliary roll located between the usual whip roll and the warp beam is mounted upon a movable frame which is raised and lowered as the warp tension increases and decreases, the varying motion of the auxiliary roll operating to change the resistance offered by the friction disks to the movement of the warp beam sothat as the tension'increases in the warp threads-the resistance to movementof the beam will be reduced.

With these and other objects inview which Fig. 2 1s a rear elevation of one end of my improved let-off taken in the direction of arrow 2, Fig. 1, i

Fig. 3 is a horizontal section on line 3-3 of Fig. 1 with the warp beam and driving gear therefor omitted,

Fig. 4is an enlarged vertical section on line 4-4 of Fig. 1, and

Fig. 5 is a detail vertical section on line 55 of Fig. 2 showing a convenient manner for holding certain elements of the friction device against angular. motion.

Referring to the drawings'I have shown the rear portion of the loom frame 10 and have indicated a warp supporting stand 11 bolted to the loom frame. In certain classes of looms where the warp is relatively inelastie a framework similar to that indicated at 11 is used to give increased length to the warp threads so that they will not break when the harness frames are shifted. The warp beam 12 is provided with gudgeons, one of which is indicated at 13 to be received by an open bearing 14 on the frame 11. Awhip roll 15 supported by uprights 16 provide a fixed guide for the warp W supplied by the beam 12. The warps extend forwardly or to the left as viewed in Fig. 1 from the whip roll and may be separated by the'harness frames not shown to define sheds. There is secured to the beam 12 a large gear'17 which rotates with the beam and is mounted on one of the gudgeons 1.3. The matterthus far described is very common and forms no part of my present invention.

In carrying my invention into effect I provide a form of let-off which has been demonstrated to be very uniform in its action, the motion includingmovable and fixed disks which are pressed together under varying pressures depending upon the tension of the warp which is supplied by the beam. When the warp becomes tight the disks will be separated to reduce friction and permit an easier movement of the warp beam. In carrying my invention into effect I provide a lever 20 secured to each end of a rock shaft 21 which is supported by the stand 11. Extending be tween levers 20 is a rotatable roll 22 under which the warp threads WV extend. The levers 20 being secured to the shaft insure even movement in a vertical direction of both ends of the auxiliary roll 22. One of said levers 20 is provided with a projecting stud 23 as shown in Figs. 1 and 3 to extend through a slot 24 formed in an arm 25 the left hand end of which is weighted as at 26 as shown in Figs. 1 and 3.

The arm 25 has a hub 27 which is threaded to receive the threads of a screw stud 28 shown in detail in Fig. 4. Said stud is provided cap to be clamped down tightly on the jour-' nal 30 to prevent angular movement thereof.

Bracket 34 has bearing portions 37 and 38, respectively, which are provided with caps 39 and 40, respectively, to confine a short shaft 41. A pinion 42 is keyed as at 48 to said shaft 41 and meshes with the large gear 17 so that movement of the beam 12 is accompanied by a corresponding movement of the shaft 41.

The friction element which resists movement of the beam includes a disk 44 keyed as at 45 to the shaft 41 and said disk 44 extends between friction disks 46 and 47 (preferably formed of leather) which are secured to plates 48 and 49, respectively. Said plates are each notched as at 50 to receive a web 51 formed on the bracket 34. The web substantially fills the notches 50 and serves to hold the plates 48 and 49 against appreciable angular movement.

The screw 28 is sufliciently long to extend through the hub 52 of the plate 48, but said hub is not threaded, being provided with a clear bore 53 so that said hub may move longitudinally along the screw without angular movement. To facilitate this I find it expedient to make the screw 28 with square threads as shown more particularly in Fig. 4. The other plate 49 may if desired have a bushing 54 interposed therebetween and the shaft 41 and said bushing may also be received between the bearing 37 and cap 39.

In operation the continued operation of the loom will make demands for more warp which must be supplied by the turning of the beam or by the raising of the auxiliary roll 22. If the friction between the disk 44 and the leather faces 46 and 47 of the plates is sufiiciently high to prevent angular movement of the shaft 41 the pinion 42 will hold the gear 17 against movement and the beam will be held relatively stationary. As weaving continues the necessary warp will be provided by an upward movement of the auxiliary roll 22. As this roll rises the stud 23 extending through the slot 24 will raise the arm 25, moving the same in a clockwise direction around the screw 28 as viewed in Fig. 1. The screw is of such a hand that upward movement of the arm 25 will cause the hub 27 to move toward the shoulder 29 and away from the hub 52 of the plate 48. Said plate, therefore, is free to move longitudinally with respect. to the shaft 41 to move the face 46 away from the disk 44. It will be noted that the disk 47 will remain substantially stationary but by reason of the keyed connection between the disk 44 and the shaft 41 said disk 44 may follow the leather facing 46 in a movement to the left as viewed in F 4. It may be assumed that the disk 44 floats lengthwise along shaft 41 but is not free to rotate thereabout. As soon as the pressure between the disk 44 and the adjacent leather faces or disks 46 and 47 has been reduced the shaft 41 and pinion will be free to rotate and the beam 12 can rotate about its gudgeons to unwind warp. As the beam rotates the auxiliary roll 22 will be permitted to descend bv the increased length of warp between said beam and the whip roll and the hub 27 of the arm 25 will again move to the right as viewed in Fig. 4 to increase frictional contact between the disks and thus offer an increased resistance to the movement of pinion 42 and the beam 12.

It will be seen that at all times the tension on the warp threads W is created by the auxiliary roll 22 and that as soon as the beam 12 begins to turn to supply more warp the auxiliary roll will immediately begin to descend, thereby maintaining proper tension on the warp threads. In Fig. l the parts are shown in full lines in the position they will assume when the warp is sufficiently tight to lift the auxiliary roll, this condition corresponding to a movement on the part of the disks to lessen the friction between them to permit movement of the warp beam and in said figure the dotted line position of the levers 2O and arm 25 with associated parts indicate the position these members assume when sulfioient warp has been unwound to lock the beam against further warp supplying movement.

By loosening the cap 35 and effecting a A slight angular movement of the screw 28 by means of the head 32 the position of the levers 20 and arm 25 may be adjusted so as to lock the beam in any desired position of said levers and arm within certain limits. If the parts are in. the-position shown in full lines in Fig; 1 maximum effect onthe screw is caused by any vertical movement either up or down with the auxiliary roll but if this movement is found to be too great screw 20 can be given an angular setting so as to permit the levers 20 and arm- 25 to assume relatively oblique posiions so that a greater motion on the part of the auxiliary roll will be required to produce a given angular motion of the hub 27 relatively to the screw. It is to be understood of course that the screw is normally held in fixed position by the cap35. It will further be evi-- dent that the angular position of the screw may be varied so as to effect adjustments in the settings of the cooperating leverage.

From the foregoing it will be seen'that I have provided a pair of rolls around which the warpextends from the warp beam toward weaving position, one of said rolls being rela-' tively fixed to establish the correct plane for the warp threads and the other roll being movable under influence of a high tensioned warp to relieve frictional resistance to the movement of the warp beam.

Having thus described my invention it will be seen that changes and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the invention and I do not wish to be limited to the details herein disclosed, but what I claim is z 1. In a let-oif motion for a loom having a warp beam pivotally mounted in fixed bearings and a whip roll in substantially fixed position, an auxiliary roll under which the warp threads pass, levers moving about a fixed pivot to support said auxiliary roll, a plurality of friction elements each having a friction surface, one of the elements being operatively connected to but mounted independently of and out of contact with the warp beam, a fixed screw, an arm threaded on the screw and having operative contact with one of the le vers which support the auxiliary roll, and means to cause said arm to move along the screw to increase or reduce the friction between said elements to offer varying degrees of resistance to the movement of the beam.

2. In a let-off motion for a loom having a Warp beam pivotally mounted in fixed bearings and a whip roll in substantially fixed position, an auxiliary roll under which the warp threads extend, supporting levers for the roll moving about a fixed center, a screw held normally in fixed position, an arm threaded on and movable alongthe screw, means establishing operative connection between one of the levers which supports the auxiliary roll and said arm, said connections being preserved for all positions of the arm along the screw, and relatively movable friction elements one of which is operatively connected to the warp beam and another of which is to be engaged by the arm, and another of which is limited as to: movement in one direction longitudinally .of the screw, movement of the-arm along the screw varying the pressure between said elements to vary the resistance offered to the -movement of the warpbeam.

3. In a let-offmotionfor a loombavinga warp beam pivotally mounted in fixed bearings and a whip roll in substantially fixed position, anauxiliary roll'under which the warp extends, means to cause said beam to move as a whole about a fixed pivot, an arm havingoperative contact with the means, a fixed screw upon which said arm is threaded, said arm being moved along the screw, a disk operatively connected to and moving with the beam, and a plate located on each sidezofzsaid.

disk, one of said plates being limited as to' movement in one direction longitudinally of the screw and the other plate to be engaged by the arm, pressure plates being dependent uponthe angular position of the arm relatively to the screw, said. auxiliary'roll moving as a whole around the aforesaid fixed axis tovary the relative angular positionof the screw and arm.

4. In a friction element for. the warp beam of a loom, a disk movable with the warp beam, a pair of plates held against substantial angular movementone located on each side of the disk, .a movable arm dependent for its positionupon the .tensionof the warp, a normally fixed screw 1 on which said arm is threaded, said arm to have contact with one. of .the'plates and the other of said. plates to be limited .as. to movement in the direction of. thelength :of the screw, and means to give said screw a plurality of angular positionsrelatively to the plates, relative angular movement of the arm and screw changingthe frictional resistance betweentherdisks and the 1 plates.

5..In a let-off for a loom having a frame and a warp beam. rotatable 'zin 'theframe, a friction element movable with the warp beam, a secondfrictionrelement to engage-the first element to resist movement of the :latter and the warp-beam, a ,screwamember, means to hold said. screw member in thesframe in: any oneof a plurality, ofangular'positions, and a device threaded on the screw and movable thereonto engage; one ofusaid friction ele ments to move the same against the other element, said device being dependentaipon the tension of the warp to determinethe extent of its movement andthe extent of. presv sure exerted between the elements, said screw by being'given this angular positionivarying the normal pressure betweenthe elements, saidscrew being normallyfixed duringmovement of the device thereon.

6. Ina let-oifqfor a looiuhaving a warp beam mounted c for rotary motion," a frame, a whip roll, an auxiliary 'roll around which the -warp extends,- a bracket mounted on betweensaid disk and.

the frame and having bearings thereon, a shaft rotatably mounted in said bearings, a friction element mounted on said shaft and capable of angular and longitudinal motion, a bearing supported by the bracket, a screw stud held from angular motion in said bearing, a second friction ele ment mounted on said screw and being held from rotary but capable of longitudinal motion to have contact with the first named element, an arm threaded on said screw, and means to give the screw a plurality of angular positions relatively to the elements, re ative movement of the arm and screw changing the frictional contact of the elements.

7. In a let-off for a loom having a warp beam mounted for rotary motion, a frame, a whip roll, an auxiliary roll around which the warp extends, a bracket mounted on the frame and having bearings thereon, a shaft rotatably mounted in said bearings, a friction element mounted on the shaft and capable of angular and longitudinal motion, an arm extending from the bracket and having a bearing, a screw stud held normally in fixed position but mounted for angular motion in said bearing, a second frictional element mounted on said screw and being held from angular but capable of longitudinal motion and to have contact with the first named element, an arm threaded on the screw, means to give the screw a plurality of angular positions relatively to the elements relative movement of the arm and screw changing the frictional contact of the elements, and additional means to hold the screw in a plurality of angular positions.

8. In a let-off motion for looms having a warp beam which is rotatably mounted, a whip roll mounted in fixed position, a movable roll under which the warp extends, a friction element mounted to have operative engagement with the warp beam, a shaft on which the element is mounted, a fixed screw having a second element mounted for longitudinal movement thereon, an arm mounted on the screw to have operative engagement with the second named element, a lever mounted for movement around a fixed pivot, and variable weighted means mounted to have operative engagement with the arm and lever tending to give said arm an angular movement and being mounted intermediate the pivot for the lever and the fixed screw, said weighted means by its angular move ment tending to give the element mounted on the fixed screw a motion in a direction of the length of the screw.

9. In a let-off motion for a loom having a warp beam which is mounted for rotary motion, a whiproll, a floating auxiliary roll around which the warp extends, a device including a shaft mounted for rotary movement, a pair of friction elements mounted on mounted on the second named arm and a variable weighted means mounted on the arms tending to give the said arms an angular movement to move the third friction element along the screw into engagement with the first friction element mounted on said. shaft whereby the rotation of said shaft is held from further rotation due to the contact of the frictional elements.

In testimony whereof I have hereunto alfixed my signature.

ELBRIDGE R. HOLMES. 

